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Friday, July 08, 2005

Doing the things a particle can

Now that summer is here, I've started reading the Feynman Lectures on Physics. I'm sure that when we actually get to classical mechanics/electromagnetism/etc., the content will become more timeless. The first few lectures are fascinating, but in a very different way than the later ones promise to be. He's giving an overview of what we do and don't know in physics, as well as the other sciences, and it's just amazing to see how much they didn't know in 1963. Well, there's probably even more that we (consciously) don't know today, but I mean how much they didn't know (and were conscious of not knowing) that we now know. I'm not saying this to be snotty, or to gloat about having been born on the shoulders of giants, but just to point out that this historical document provides a snapshot in the history of science, and proves that venerated breakthroughs don't happen overnight.

For example, the state of fundamental particles was a mess in 1963. They had discovered all sorts of crazy new particles in accelerators, and just a few years before the quark model took hold, we read:

It turns out that today we have approximately thirty particles, and it is very difficult to understand the relationships of all these particles, and what nature wants them for, or what the connections are from one to another. We do not today understand these various particles as different aspects of the same thing, and the fact that we have so many unconnected particles is a representation of the fact that we have so much unconnected information without a good theory. After the great successes of quantum electrodynamics, there is a certain amount of knowledge of nuclear physics which is rough knowledge, sort of half experience and half theory, assuming a type of force between protons and neutrons and seeing what will happen, but not really understanding where the force comes from. Aside from that, we have made very little progress. We have collected an enormous number of chemical elements. In the chemical case, there suddenly appeared a relationship among these elements which was unexpected, and which is embodied in the periodic table of Mendeleev. For example, sodium and potassium are about the same in their chemical properties and are found in the same column in the Mendeleev chart. We have been seeking a Mendeleev-type chart for the new particles.

Wow. So now we have that Mendeleev-type chart (it's called the Standard Model), and we're left with a different question: WHY? Why do these particles have the masses, charges, etc. that they do? So to keep the chemistry analogy going, we're at the point of having the periodic table, but before they discovered electrons and atomic orbitals and all that. Maybe string theory is the answer, maybe it isn't.

Moving into the biology section, I don't know nearly as much about biology, but some things jumped out. I'm guessing that GDP and GTP (guanadine-di-phosphate and guanadine-tri-phosphate) are what I learned as ADP and ATP (adenosine diphosphate and adenosine triphosphate), and that "microsomes" are what we now call ribosomes.

So in 1963, it appears that they understood the structure of DNA, and knew that the nucleotides coded for the amino acids, but had no idea how -- the genetic code was still on its way.